You can upload anything you want to the Muse blockchain. It's the streaming platforms that are legally on the hook if they play copywritten stuff to their users. So if you want anyone to actually hear it, you need to make sure you own the rights. Only then will a streaming platform comfortably display your music on its site.

Same relationship as Steem and Steemit/busy.org/dmania.lol (and the other Steem front-ends)